Recently, realization of drug discovery screening to develop new medicines or regenerative medicine to complement the lost function of organs, both using tissues/organs induced from pluripotent stem cells such as iPS or ES cells, has attracted attention (Takebe, et al., Nature, 499: 481-484, 2013 (Non-Patent Document No. 1); WO2013/047639 A1: Method for producing tissue and organ (Patent Document No. 1)).
In order to realize regenerative medicine for liver diseases using human iPS cells, a technique for producing “a vast quantity” of human hepatocytes of GMP grade is required. For example, in order to enable about 30% function replacement of human adult liver, it is essential to transplant and engraft 6×1010 hepatocytes per patient. Speaking of the production of this vast quantity of human hepatocytes, a cost estimate by the present inventors has revealed that when an attempt is made to prepare cells by a differentiation inducing protocol according to an existing prior art technology, a treatment of one patient on a waiting list for liver transplantation requires a huge cost amounting to approximately 9.5 billion yen if transplantation efficiency is taken into account.